Forged from 1020 Carbon Steel, Apex Pro looks very similar to Callaway's 2013 X Forged iron, with a similar blade length, top line and sole. However, the new iron has a number of technological improvements.

One of the noticeable additions to Apex Pro is a high-density tungsten insert that was strategically placed on the sole of the long irons (2-5), lowering the center of gravity (CG) for a higher launch with more carry. The lower CG also makes the long irons more forgiving as well.

Along with altering the CG Height Progression in the long irons, Callaway engineers made the center of gravity progressively higher in the short irons, giving them a flatter trajectory with less spin for more control on approach shots.

The CG Height Progression also allowed engineers to make the faces of the irons 17 percent thinner than those of the 2013 X Forged, increasing ball speed slightly. To ensure sound and feel weren't compromised by the thinner face, a high damping polymer insert was added to the cavity of the iron to eliminate unwanted vibrations at impact.

Another new addition to Apex Pro is a new 37WV groove design that delivers a higher launch out of the rough for more distance. Through extensive research, Callaway found that Tour players and better amateurs were often generating too much spin out of the rough, due in large part to high club head speed.

Compared to X Forged, which had 20-degree V grooves that were spaced closer together, Apex Pro has 37-degree side walls and V grooves that are spaced farther apart.

According to Callaway officials, Apex Pro is expected to be the company's most used iron on the PGA TOUR this season.

Callaway's Apex Pro (4-PW) will be available Jan. 15 for $1,100 with KBS' new Tour-V steel shaft, or $1,300 with UST Mamiya's Recoil 600 Series graphite shaft.